Current practices for measuring signal parameters of a received electromagnetic signal involve using multiple synchronized receivers. Signal parameters include relative amplitude and correlation between received signals. A received signal may be distributed among multiple signal branches of a measuring system. A signal branch refers to a path for the distribution of one or more received electromagnetic signals. The path of the signal branch may include a transmission media (e.g., coaxial cable) or may be integrated into a circuit board (e.g., microstrip). For each signal branch, a separate receiver typically is required to measure the signal parameters associated with a corresponding signal branch. The requirement for multiple receivers tends to increase the size, weight, and cost of the conventional measuring system.
To obtain accurate correlation measurements between signal branches, all receivers are synchronized using a highly stable external oscillator (e.g., stability better than 10 parts per million of the oscillator frequency). All receivers are calibrated for amplitude variations from unit to unit to reduce errors in the relative amplitude measurements. However, the synchronization and amplitude calibrations are time-consuming and subject to human error. Moreover, each receiver may experience relative amplitude drift due to differences in temperature from receiver to receiver. Thus, a need exists for an improved measuring system which eliminates or expedites the calibration process, including its temporal and amplitudinal aspects.
The reception of received electromagnetic signals may sometimes be improved through the use of diversity antennas. Yet, the full benefit of diversity gain is often lost because the receiving system lacks the necessary sophistication to accurately decide whether or not to combine signals from different diversity branches of the diversity antenna. Thus, a need exists for a measuring system that may be incorporated into a receiving system to enhance reception of received electromagnetic signals through an accurate analysis of signal parameters.